A conventional wireless network system has focused on maximization of spectrum efficiency so as to provide users with more improved services. Thus, since energy consumption of the system explosively increases, there is a need to develop a new system capable of enhancing efficiency of energy consumption and optimizing spectrum efficiency according to the environment problems.
Optimization of energy efficiency may be denoted by the ratio of an achievable sum rate to the total power consumption of the system. Energy efficiency optimization may be interpreted as the fractional programming issue for solving fractional problems, and unexpected problems may occur due to nonlinearity. Although the energy efficiency issue may be interpreted to be pseudo concave in an environment in which there is no multi-user interference, application of the above-mentioned method to be applied to a general situation in which multi-user interference exists is difficult.
Therefore, many developers and companies are conducting intensive research into various methods for optimizing energy efficiency in the multi-user interference situation. For example, a method for converting fractional programming indicating unique characteristics of the energy efficiency problem into the linear problem, and solving the energy efficiency problem has recently been proposed. However, in order to implement the above-mentioned solutions, all channel information and the additional information must be exchanged, and the algorithm must be repeatedly carried out according to a time-variant channel. Therefore, an improved method for optimizing energy efficiency is needed.